Art of making electrolytic iron



f F. A. EUST|S`ET AL ART 'OF MKING ELECTROLYTIC IRON Orlgnal Filed Dec.l7

l /mes fone status entre Parser estres,

FREDERIC A. EUSTIS, OF MILTON, CABLE R. HAYWAED, QF QUINCY, AND HENRY M.SCHLEICHER AND DONALD BELCHER, OF BOSTGN,I*IASSVACHUSETTS, ASSIGNORS, BYDIRECT AND MESNE ASSIGNMENTS, OF ONE-HALF TO SAID EUSTS AND ONE-HALF T0CHARLES PAGE PERIN, OF NEW YORK, N. Y.

ART 0F MAKING ELECTROJYTIC IRON.

Original application filed December 1, 1920, Serial No. 427,541. Dividedand this'application ed July Serial No. 482,928.

lpreparation of the ferrous solutions suitable for the electrolyticdeposit of' iron.

The present application is a division o'f an application ,filed by usDecember 1, 1920,

Serial No. 427,541, now Letters Patent of the United States No.1,412,174, dated April 1 1-, 1922, ,and is addressed particularly tothat modification of the invention .described in our ,said formerapplication employing' an electric current for reducing the ferriesolution in the liquor discharged from the anode compartment of theelectrolytic cell in which the i'ron is deposited. .i

The ferrous solution from'which iron is deposited by electrolysis may bea solution of ferrous chloride in Water, a ferrous sulphate solution, orindeed a solutionvcontain-v ing any` salts of iron that` will insolution dissociate to deposit iron under the action ,of electrolysis,that will form the two series of salts, ferrie and ferrous, and thatwill attack the ore or other raw material constitilting the source ofiron. By way of illustration therefore, and not of limitation, we willdescribe the processes usingr 'a ferrous chloride solution.

The ferrous 'solution when made by the method hereinafter described willcontain at least some acid or ferricsalts, sueltas ferrie chloride,although it may be only traces, and must be thoroughly neutralizedybefore it is suitable for the production of electrolyt'ic iron, becausethe presence of acid or ferrie salts causes'a 'poor iron deposit andresults in low current eiiiciency. To this end the solution is mixedwith pulverized limestone in 'a suitable tank. Limestone furnishescalcium carbonate (CaCO3) which is the most suitable agent forneutralization, as 1t has the capacity of readily precipitating Iirstferrie salts before precipitating the ferrous salts. iVehave found thatfor the best results it is advisable to use'l enough neutralizing agentto precipitate a small amount offerrous iron. lThis insures completeneutralization of the liquor, the` neutrality ,of the solution in thecathode compartment of the electrolytic cell beingJ an indispensablecon# dition for the most efficient electrolysis of iron..

The solution is then filtered if necessary heated nearly to the boilingpoint, and passed hot into the cathode compartment of a diaphragmelectrolytic celi. Under proper conditions vmetallic iron is depositedon the cathode. The liquor passes through the dia.-

ph'ragm into the anode compartment and is thence returned to the processto be used in making more ferroussolution as hereinafter l described.

The accompanying drawing illustrates dia-Y grammatically apparatus forperforming the y process.

A special electrolysis celi is used for depositing the iron, ofthe kindfully described in our said former patent to which reference is made fora more detailed description of its constructicnand mode of operation.

The` hot anode liquor containing ferrie chloride and ferrous chloride{or ferrie andA ferrous sulphates. if the loriginal solution was asulphate instead of a chloride) is discharged from the vmainelectrolysis cell A in which the iron is deposited, into a secondelectrolytic cell `Gr i'vhich may be termed an electrolytic reducingtank. The application of electric energy to the ferrie solution in theelectrolytic reducing tank G, Wiil reduce the solution from the ferrieto ferrous state. This 'reduction of the ferrie salts formed inelectrolysis ceil A furnishes acid needed for dissolving the ore. Theferrous soiution resulting from this electrolytic reducing stepconstitutes a leach liquor by which the iron 'may be dissolved from thecre. The reduced leach` liquor is then. put on the ore in a s0111- tiontank B where it dissolves iron from the ore and is` then filtered at C.Thence the major part of the solution is pumped back to thereducingtank, G, While the smaller part of the solution which vmay still be`slightly acid will be ladvanced tofthe limel stone tank D in which itWill vbe neutralized. The solution from the limestone tank Dis thendelivered hot, Vpreferably at a tempera-` ture in the `region of theboiling point, tothe electrolysis cell A for. the deposit of iron,andthe cycle repeated.

The part of the solution sentv to the limestone tank D may optionally bepassed through a tank F containing scrap iron for the'purpose of furtherenriching the solution in iron and at the same time using up `part ofthe acid coming from the solution tank B before it, enters the limestoneneutralizing 4tank' D. i y l It is desirable to' rovide agitation ofsome sort in thefsolution tank B. v l Thelreason for returning thegreater part of the liquor from the ore solution tank to the reducingcell is that the electofthe action .of the leach liquor' on'mostoxidized ores is to take iron into solution in ferrie state; therefore,the solution coming from the ore solution tank will contain ferric saltsand mu'st.again be reduced.V

If alltleliquor were sentdirect tothe limestone neutralizing tank itwould be necessary to use large amounts of limestone for neutralizationbecause.. ofv the large amount of ferrie chloride present in ythesolution dissolved from the ore. This isnot.

only costl in limestone but may use` up too much aci in theneutralization step. There- .ore', a part of the solution issent fromthe ore solution tank back to the reducing cell Where the ferriechloride dissolved from the l ore is reduced, and the solution soreduced upon again passing over the'cre picks up more ferrie iron butonly one third as much as was present immediately before .it wasreduced. Thus by repeatedly cycling part ofthe solution through. thereducino' tower andover the ore the ferrie iron in Athat part of thevsolution advanced to the limestone tank4 may be diminished toany pointdesired.

Since no acid is added for reductiongby the present method, but onlyelectricalwenergy,"

there is no source of nevvl acid in the cyclic process itself and theacid must therefore be carefully conserved. This can be done by turninga large portion of the'solution from the ore solution tank back to thereducing cell and advancing only a small portion to the limestone tankfor I ieutralizngf.l Even with this mode vthere is some .ofl acid whichcan economically be restor by blow- SO2 gas into the liquor in thereducing or at some other convenient point. When the' reduction of theanode liquor is performed by an electrolytic reducing cell,

vtank B. y v l s For a further division of the aforesaid ap? solvent.Many oxide ores occur in nature in fine condition and such will requireonly a final pulverizing treatments The mixture in the solution tankshould be maintained at a high temperature, vas the hotter the mixturethe more effective is the action. Good results maybe obtained at a.temperature of C. and above. It is also desirable to'stir or agitate themixture in order'to insure constant contact of active solvent 'with thtJore; or percolation may be used. A counter-currentmethod of leaching isadvised, f

.by which fresh ore is treated yvithlthe Weakest solution and theresidue of the ore is `treated with fresh solution.

The process above described is particu-v larly adapted to thetreatmentIof oxidized ores of iron, such as limonite, liematite or magnetite, asthe source'of iron, since the anode liquor resulting from the use 'ofoxidized ores contains bothl ferrie and ferrous vchloride or sulphateand should be reduced to a ferrous state in order to make an effectivesolvent for the ore. It might also be used `for the treatment of'sulphide ore if the sulphideore isv of-suchcliaracter that the reductionof the solution Will not readily take place in the solution'tank alongwith the solution of theliron, t can better be performed 'asa separate sep after the liquor is vdischarged from the electrolysis cell- A andbeforeit is put into the soli'ition plication Serial No. 427,541,reference is made to an application Serial No. filed by us July 7, 1921.

We clairnz-Y l. The art of -making electrolytic'iron which comprisesreducing a ferrie solution by means of an electric current to aferrousieaeee,

state, and then transferring the ferrous lution to a separateelectrolytic cell lto which the ferric. solution has no access and depositing iron from the ferrous solution by electrolysis in said separatecell.

2. The artA of making electrolytic iron which comprises reducing aferric solution by means of an electric current,v leaching au iron orewith the reduced solution, and de0 y positing iron from" the leachliquor by.elcctrolysis.

3.. The artl of making electrolytic iron which @reprises reducing aferricnsolutionmisf by means ofen electric current, leaching an oxidizediron ore with the reduced solution and depositing iron from the leachliquor by electrolysis.`

' A. The art of making electrolytic iron which comprises reducing uferrie solution by means of an electric current, leaching un iron orewith the reduced solution, neutralizing the solution und depositing irontherefrom by electrolysis.

5. The art;- of. markingA electrolytic iron which comprisesv reducingferrie solution by means of an'electro current, leaching an iron orewith the reduced solution, maintaining the solution at :1 temperature inthe region of the boiling point und depositing iron from the solutionWhile hot hy electrolysis.

l. ign/eu by us this 5th duyoi" July, 1921. v

FREDERIC A. EUSTIS. CABLE R. HAYWARD. HENRY M. S-(IIILEICHER. DONALDBELUHER.

